The Gray Wolf

THE GRAY WOLF

The gray wolf or grey wolf is a species of canid native to the wilderness and remote areas of North America, Eurasia, and North Africa. It is the largest member of its family, with males averaging 43–45 kg (95–99 lb), and females 36–38.5 kg (79–85 lb). It is similar in general appearance and proportions to a German shepherd, or sled dog, but has a larger head, narrower chest, longer legs, straighter tail and bigger paws. Its winter fur is long and bushy, and predominantly a mottled gray in colour, although nearly pure white, red, or brown to black also occurWithin the genusCanis, the gray wolf represents a more specialised and progressive form than its smaller cousins the coyote and golden jackal, as demonstrated by its morphological adaptations to hunting large prey, its more gregarious nature and its highly advanced expressive behavior. It is a social animal, travelling in nuclear families consisting of a mated pair, accompanied by the pair's adult offspring. The gray wolf is typically an apex predator throughout its range, with only humans and tigers posing a serious threat to it. It feeds primarily on large ungulates, though it also eats smaller animals, livestock, carrion, and garbage.

The gray wolf is one of the world's most well researched animals, with probably more books written about it than any other wildlife species. It has a long history of association with humans, having been despised and hunted in most agricultural communities due to its attacks on livestock, while conversely being respected by some Native American tribes. It is the sole ancestor of the dog, which was first domesticated in the Middle East. Although the fear of wolves is prevalent in many human societies, the majority of recorded attacks on people have been attributed to animals suffering from rabies. Non-rabid wolves have attacked and killed people, mainly children, but this is unusual, as wolves are relatively few, live away from people, and have been taught to fear humans by hunters and shepherds. Hunting and trapping has reduced the species' range to, though its still relatively widespread range and stable population means that the species is not threatened at a global level, and is therefore classified by the IUCN as Least Concern.

The species' most likely ancestral candidate is , a small, narrow skulled North American canid of the Miocene era, which may have also given rise to the coyote. After the extinction of the large bodied family, developed into a larger, broader-skulled animal. Fossils of this larger form of found in northern Texas may represent the ancestral stock from which true wolves derive. The first true wolves began to appear at the end of the Blancan North American Stage and the onset of the early Irvingtonian. Among them was , a small species closely resembling the modern-day red wolf, which colonised Eurasia by crossing the Bering land bridge. The new Eurasian population gradually evolved into , which closely resembled modern wolves found in the Arabian Peninsula and South Asia, which were once distributed in Europe in the early Quaternary glaciation until about 500,000 years ago .

MtDNA studies have shown that there are at least four distinct gray wolf lineages: the most ancient is that of the African wolf native to North, West, and East Africa, which is thought to have originated as early as the Middle to Late Pleistocene. All other lineages occur together in the Indian Subcontinent, the oldest of which is the Himalayan wolf native to the region of eastern Kashmir, Himachal Pradesh, parts of Tibet and eastern Nepal, which is thought to have originated 800,000 years ago, when the Himalayan region was going through major geologic and climatic upheaval. The peninsular Indian wolf, likely diverged from the Himalayan wolf 400,000 years ago.The youngest wolf lineage in India is represented by C. l. chanco (native to the northwestern Himalayan region of Kashmir), which originated 150,000 years ago. This last lineage, known as the Holarctic clade, expanded into Europe and North America, as shown by it sharing genetic markers with domestic dogs, European and North American wolves.

The now extinct Japanese wolves were descended from large Siberian wolves which colonised the Korean Peninsula and Japan, before it separated from mainland Asia, 20,000 years ago during the Pleistocene. During the Holocene, the Tsugaru Strait widened and isolated Honshu from Hokkaidō, thus causing climatic changes leading to the extinction of most large bodied ungulates inhabiting the archipelago. Japanese wolves likely underwent a process of island dwarfism 7,000–13,000 years ago in response to these climatological and ecological pressures. formerly native to Hokkaidō, was significantly larger than its southern cousin , as it inhabited higher elevations and had access to larginteraction with dispersing wolves from Siberiaer prey, as well as a continuing genetic.

As of 2005, 37 subspecies of gray wolf are recognised by MSW3. Included among them are the domestic dog and the dingo, as well as the Eastern wolf of Algonquin Provincial Park and the red wolf of North Carolina. Once thought to be unique species, SNP studies show that the red and Eastern wolf are in fact the results of varying degrees of wolf-coyote stretching back to only a few centuries. The Eastern wolf is on average 58% gray wolf, while the red wolf is only 20–24%. Phylogenetic comparisons of the MtDNA sequences of both wolves and golden jackals in 2011 demonstrated that the African wolf, which was once thought to be a golden jackal, is in fact a subspecies of gray wolf.

Wolf subspecies are divided into two categories:

"Northern wolves": large-sized, large-brained wolves with strong carnassials which inhabit North America, Europe and northern Asia."Southern wolves": native to the Arabian Peninsula, South Asia and possibly North Africa. They are characterised by their smaller size, skull and teeth, and a short and thin coat without appreciable underwool. They may represent a relict population of early wolves, as they closely resemble fossil European wolves. The rate of changes observed in their DNA sequences date them to about 800,000 years, as opposed to the American and European lineages which stretch back only 150,000.The vocalisations of southern wolves have a higher proportion of short, sharp barking,and they seldom howl. It is likely that dogs and dingoes stem from this group.

Wolves in Central and East Asia are intermediate in form and size to northern and southern wolves. Differences in brain size are well defined in different wolf populations, with wolves in northern Eurasia having the highest values, North American wolves having slightly smaller brains, and the southern wolves having the smallest about 5–10% smaller than those of northern wolves.

Although dogs and wolves are genetically very close, and have shared vast portions of their ranges for millennia, the two generally do not voluntarily interbreed in the wild,though lone wolves may fraternise with guard or herding dogs as surrogate pack members.They can produce viable offspring, with all subsequent generations being fertile. In North America, black colored wolves acquired their coloration from wolf-dog hybridization, which occurred 10,000–15,000 years ago.Although wolf-dog hybridisation in Europe has raised concern among conservation groups fearing for the wolf's purity, an analysis on the mtDNA sequences show that introgression of dog genes into European wolf populations does not pose a significant threat. Also, as wolf and dog mating seasons do not fully coincide, the likelihood of wild wolves and dogs mating and producing surviving offspring is small.Like pure wolves, hybrids breed annually, though their mating season occurs three months earlier, with pups mostly being born in the winter period, thus lessening their chances of survival.Although it is popularly believed that some Inuit tribes mate their sled dogs to wolves in order to improve their stamina, this is probably untrue, as wolf hybrids are generally unable to cooperate effectively in pulling harnesses, and their stamina is much less than that of sled dogs. The captive breeding of wolf-dog hybrids has proliferated in the USA, with 300,000 such animals being present there. The most commonly used dog breeds for this purpose are of the spitz group. At least two wolf-dog breeds have been created in Europe, the Saarlooswolfhond and the Czechoslovakian Wolfdog, both by crossing wolves with German shepherds.

Numerous genetic studies indicate that North American gray wolves have hybridized with coyotes in varying degrees in different areas. Studies on mtDNA and microsatellite loci indicate that wolves have hybridized extensively with coyotes in the northeastern USA and southeastern Canada, with the frequency of coyote haplotypes in wolves tending to increase to the east, from 50% in Minnesota, to 100% in southern Quebec. These hybrids are smaller than wolves, and hold smaller territories, but are in turn larger and hold more extensive territories than coyotes. In 2011, an analysis of 48,000 SNP chips in the genomes of various wolf and coyote populations revealed that the eastern wolf native to Algonquin Provincial Park and the red wolf native to North Carolina, both previously labeled as species distinct from the gray wolf, are in fact products of varying degrees of wolf-coyote hybridization. The wolf-coyote admixture resulting in the development of the eastern wolf may have occurred on the order of 600–900 years ago between gray wolves and a now extinct pre-Columbian coyote population. The eastern wolf has since backcrossed extensively with parent gray wolf populations. The red wolf may have originated later, approximately 287–430 years ago, when much of the southeastern USA was being converted to agriculture and predators were targeted for extermination. During this period, declining local wolf populations would have been forced to mate with coyotes, with the resulting hybrids backcrossing to coyotes as the wolves disappeared, to the extent that ,75–80% of the modern red wolf's genome is of coyote derivation. Although hybridization between wolves and golden jackals has never been observed, evidence of such occurrences was discovered through mtDNA analysis on jackals.

The gray wolf is a slender, powerfully built animal with a large, deeply descending ribcage and a sloping back. Its abdomen is pulled in, and its neck heavily muscled. Its limbs are long and robust, with comparatively small paws. The front paws have five toes each, while the back paws have four. The forelimbs are seemingly pressed into the chest, with the elbows pointed inward, and the feet outward, thus allowing both fore and hind limbs on the same side to swing in the same line. The wolf's legs are moderately longer than those of other canids. This enables the animal to move swiftly, and allows it to overcome the deep snow that covers most of its geographical range. Females tend to have narrower muzzles and foreheads, thinner necks, slightly shorter legs and less massive shoulders than males. Compared to its smaller cousins the coyote and golden jackal, the gray wolf is larger and heavier, with a broader snout, shorter ears, a shorter torso and longer tail.

The gray wolf's head is large and heavy, with a wide forehead, strong jaws and a long, blunt muzzle. The ears are relatively small and triangular. The teeth are heavy and large, being better suited to crushing bone than those of other extant canids, though not as specialised as those found in hyenas. The canine teeth are robust and relatively short (26 mm).The wolf can exert a crushing pressure of perhaps 1,500 lbf/incompared to 750 lbf/in for a German shepherd. This force is sufficient to break open most bones.In cold climates, the wolf can reduce the flow of blood near its skin to conserve body heat. The warmth of the footpads is regulated independently of the rest of the body, and is maintained at just above tissue-freezing point where the pads come in contact with ice and snow.

The gray wolf usually carries its head at the same level as the back, raising it only when alert. It usually travels at a loping pace, placing its paws one directly in front of the other. This gait can be maintained for hours at a rate of 8–9 km/hr, and allows the wolf to cover great distances. On bare paths, a wolf can quickly achieve speeds of 50–60 km/hr. A running wolf holds its head slightly low and cocked to one side, directing one ear forward and the other back. This posture allows the wolf to continually make use of its exceptional hearing.

The gray wolfhas very dense and fluffy winter fur, with short underfur and long, coarse guard hairs. Most of the underfur and some of the guard hairs are shed in the spring and grow back in the autumn period. The longest hairs occur on the back, particularly on the front quarters and neck.
Especially long hairs are found on the shoulders, and almost form a crest on the upper part of the neck. The hairs on the cheeks are elongated and form tufts. The ears are covered in short hairs which strongly project from the fur. Short, elastic and closely adjacent hairs are present on the limbs from the elbows down to the calcaneal tendons. The winter fur is highly resistant to cold; wolves in northern climates can rest comfortably in open areas at 40° by placing their muzzles between the rear legs and covering their faces with their tail. Wolf fur provides better insulation than dog fur, and does not collect ice when warm breath is condensed against it. In warm climates, the fur is coarser and scarcer than in northern wolves. Female wolves tend to have smoother furred limbs than males, and generally develop the smoothest overall coats as they age. Older wolves generally have more white hairs in the tip of the tail, along the nose and on the forehead. The winter fur is retained longest in lactating females, though with some hair loss around their nipples. Hair length on the middle of the back is 60–70 mm. Hair length of the guard hairs on the shoulders generally does not exceed 90 mm, but can reach 110–130 mm.

Coat colour ranges from almost pure white through various shades of blond, cream, and ochre to grays, browns, and blacks. Variation in fur color tends to increase in higher latitudes.Differences in coat colour between sexes are largely absent,though females may have redder tones.Fur color doesn't seem to serve any camouflage purpose, with some experts concluding that the blended colors have more to do with emphasizing certain gestures during interaction.Black coloured wolves which occur through wolf-dog hybridisation rarely occur in Eurasia, where interactions with domestic dogs have been reduced over the past thousand years due to the depletion of wild wolf populations. Black specimens are more common in North America, with about half the wolves in Yellowstone National Park being black.

The gray wolf's sense of smell is relatively weakly developed when compared to that of some hunting dog breeds, being able to detect carrion upwind no farther than 2–3 km. Because of this, it rarely manages to capture hidden hares or birds, though it can easily follow fresh tracks. Its auditory perception is sharper than that of the fox, being able to hear up to a frequency of 26 kHz,which is sufficient to register the fall of leaves in the autumn period.The urban legend that wolves fear the sound of string instruments may have a basis in fact, as captive wolves have been shown to exhibit signs of intense distress when hearing low minor chords.Its night vision exceeds. of other Canids

The gray wolf is generally monogamous, with mated pairs usually remaining together for life, unless one of the pair dies. Upon the death of one mated wolf, pairs are quickly re-established. Since males often predominate in any given wolf population, unpaired females are a rarity. If a dispersing male wolf is unable to establish a territory or find a mate, he mates with the daughters of already established breeding pairs from other packs. Such wolves are termed "Casanova wolves" and, unlike males from established packs, they do not form pair bonds with the females they mate with. Some wolf packs may have multiple breeding females this way, as is the case in Yellowstone National Park.In addition to heterosexual behavior, homosexual behavior has been observed in wolves. Male wolves often mount each other when the highest ranking female in the pack comes into heat.

Wolves bear relatively large pups in small litters compared to other canid species. The average litter consists of 5–6 pups,with litter sizes tending to increase in areas where prey is abundant,though exceptionally large litters of 14–17 pups occur only 1% of the time.Pups are usually born in spring, coinciding with a corresponding increase in prey populations.Pups are born blind and deaf, and are covered in short soft grayish-brown fur. They weigh 300–500 grams at birth, and begin to see after 9–12 days. The milk canines erupt after one month. Pups first leave the den after 3 weeks. At 1.5 months of age, they are agile enough to flee from danger.

Mother wolves do not leave the den for the first few weeks, relying on the fathers to provide food for them and their young. Pups begin to eat solid food at the age of 3–4 weeks. Pups have a fast growth rate during their first four months of life: during this period, a pup's weight can increase nearly 30 times.Wolf pups begin play fighting at the age of 3 weeks, though unlike young foxes and coyotes, their bites are inhibited. Actual fights to establish hierarchy usually occur at 5–8 weeks of age. This is in contrast to young foxes and coyotes, which may begin fighting even before the onset of play behavior.By autumn, the pups are mature enough to accompany adults on hunts for large prey.

Wolves use different places for their diurnal rest: places with cover are preferred during cold, damp and windy weather, while wolves in dry, calm and warm weather readily rest in the open. During the autumn-spring period, when wolves are more active, they willingly lie out in the open, whatever their location. Actual dens are usually constructed for pups during the summer period. When building dens, females make use of natural shelters such as fissures in rocks, cliffs overhanging riverbanks and holes thickly covered by vegetation. Sometimes, the den is the appropriated burrow of smaller animals such as foxes, badgers or marmots. An appropriated den is often widened and partly remade. On rare occasions, female wolves dig burrows themselves, which are usually small and short with 1–3 openings.Wolves do not line their denning places, a likely precaution against parasites.The den is usually constructed not more than 500 metres away from a water source,and typically faces southwards, thus ensuring enough sunlight exposure, keeping the denning area relatively snow free.

Resting places, play areas for the pups and food remains are commonly found around wolf dens. The odour of urine and rotting food emanating from the denning area often attracts scavenging birds such as magpies and ravens. As there are few convenient places for burrows, wolf dens are usually occupied by animals of the same family. Though they mostly avoid areas within human sight, wolves have been known to nest near domiciles, paved roads and railways

Although social animals, single wolves or mated pairs typically have higher success rates in hunting than do large packs, with single wolves having occasionally been observed to kill large prey such as moose, bison and muskoxen unaided.A wolf hunt can be divided into five stages:

Locating prey: The wolves travel in search of prey through their power of scent, chance encounter, and tracking. Wolves typically locate their prey by scent, though they must usually be directly downwind of it. When a breeze carrying the prey's scent is located, the wolves stand alert, and point their eyes, ears and nose towards their target. In open areas, wolves may precede the hunt with group ceremonies involving standing nose-to-nose and wagging their tails. Once concluded, the wolves head towards their prey.

Wolves howl to assemble the pack usually before and after hunts), to pass on an alarm particularly at a den site, to locate each other during a storm or unfamiliar territory and to communicate across great distances.Wolf howls can under certain conditions be heard over areas of up to 130 km (50 sq mi).Wolf howls are generally indistinguishable from those of large dogs.Male wolves give voice through an octave, passing to a deep bass with a stress on , while females produce a modulated nasal baritone with stress on. Pups almost never howl, while yearling wolves produce howls ending in a series of dog-like yelps.Howling consists of a fundamental frequency which may lie between 150 and 780 Hz, and consists of up to 12 harmonically related overtones. The pitch usually remains constant or varies smoothly, and may change direction as many as four or five times.Howls used for calling pack mates to a kill are long, smooth sounds similar to the beginning of the cry of a horned owl. When pursuing prey, they emit a higher pitched howl, vibrating on two notes.

When closing in on their prey, they emit a combination of a short bark and a howl.When howling together, wolves harmonize rather than chorus on the same note, thus creating the illusion of there being more wolves than there actually are.Lone wolves typically avoid howling in areas where other packs are present.Wolves do not respond to howls in rainy weather and when satiated. Wolves from different geographic locations may howl in different fashions: the howls of European wolves are much more protracted and melodious than those of North American wolves, whose howls are louder and have a stronger emphasis on the first syllable. The two are however mutually intelligible, as North American wolves have been recorded to respond to European-style howls made by biologists.

Olfaction is probably the wolf's most acute sense, and plays a fundamental role in communication. The wolf has a large number of apocrine sweat glands on the face, lips, back, and between the toes. The odor produced by these glands varies according to the individual wolf's microflora and diet, giving each a distinct "odor fingerprint". A combination of apocrine and eccrine sweat glands on the feet allows the wolf to deposit its scent whilst scratching the ground, which usually occurs after urine marking and defecation during the breeding season. The follicles present on the guard hairs from the wolf's back have clusters of apocrine and sebaceous glands at their bases. As the skin on the back is usually folded, this provides a microclimate for bacterial propagation around the glands. During piloerection, the guard hairs on the back are raised and the skin folds spread, thus releasing scent.

The pre-caudal scent glands may play a role in expressing aggression, as combative wolves raise the base of their tails whilst drooping the tip, thus positioning the scent glands at the highest point.The wolf possesses a pair of anal sacs beneath the rectum, which contain both apocrine and sebaceous glands. The components of anal sac secretions vary according to season and gender, thus indicating that the secretions provide information related to gender and reproductive state. The secretions of the preputial glands may advertise hormonal condition or social position, as dominant wolves have been observed to stand over subordinates, apparently presenting the genital area for investigation. During the breeding season, female wolves secrete substances from the vagina which communicate the females' reproductive state, and can be detected by males from long distances. Urine marking is the best-studied means of olfactory communication in wolves. Its exact function is debated, though most researchers agree that its primary purpose is to establish boundaries. Wolves urine mark more frequently and vigorously in unfamiliar areas, or areas of intrusion, where the scent of other wolves or canids is present. So-called raised leg urination (RLU) is more common in male wolves than in females, and may serve the purpose of maximizing the possibility of detection by conspecifics, as well as reflect the height of the marking wolf. Only dominant wolves typically use RLU, with subordinate males continuing to use the juvenile standing posture throughout adulthood.